Known in the art is a magnet-type rodless cylinder which is provided with a base with a U-shaped cross-section which is provided with a left and right pair of side wall parts, a pair of end caps which are provided at the two ends of the base, a cylinder tube which holds a piston to be able to move back and forth in the axial direction and which is provided parallel to the side wall parts between the same, and a slide member which is passed over the cylinder tube and which is arranged between the side wall parts of the base, the piston and the slide member being magnetically coupled. Accordingly, if supplying the inside of the cylinder tube with compressed air or other fluid to make the piston move inside of the cylinder tube, the slide member can move integrally with the piston.
In such a magnet-type rodless cylinder, guide mechanisms are given for guiding the slide member with respect to the cylinder tube with a high precision. As such guide mechanisms, for example, PLT 1 discloses structures which provide inside load ball-use guide grooves at the two side surfaces of a driven table (slide member) and outside load ball-use guide grooves at inside surfaces of guide rails (base), which provide no-load ball-use guide bores at the inside of the slide member, which provide circulating paths which connect the inside load ball-use guide grooves and no-load ball-use guide bores at end caps which are fastened to the two end faces of the slide member, and which hold ball-shaped rollers at endless circulating paths which are comprised of these guide grooves, guide bores, and circulating paths.